文档： http ://docs.sencha.com/touch/2.3.0/#!/api/Ext.device.Camera-method-capture
source : String
The source of where the image should be taken. Available options are:
album - prompts the user to choose an image from an album
camera - prompts the user to take a new photo
library - prompts the user to choose an image from the library
如果我选择专辑或库，设备上也会发生同样的事情。
相机捕获中源的“库”和“专辑”有什么区别？